The objectives of this project are: 1. To investigate the regional changes in regional cerebral blood flow and the factors involved in its control by the use of chronically implanted miniature flow and O2 sensors which have demonstrated a "basic" rhythmicity in this flow; the origin and cause of this rhythmicity and its physiological significance. 2. To study the reaction of isolated anterior small branches of the anterior and middle cerebral and basalar arteries to catecholamines and its relation to the possible influence of the sympathetics on the cerebral blood flow and the possibility of an inherent rhythmicity in these mammalian cerebral vascular smooth muscles which has been denied by some investigators. 3. To investigate further the mechanism responsible for the centro-neurogenic pulmonary pathology which attends dysfunction of the CNS in severe head injury, epileptiform oxygen and Metrazol convulsions which as our earlier work has shown is mediated by the sympathetics. In this, the fluorescence technique is to be used for the determination of adrenergic nerve activity directly on the lung under these stress conditions, and its relation to the severity of the gross lung damage. 4. To examine further a) the cause of the change in pulmonary compliance which as our earlier work has shown, occurs in severe head injury and oxygen convulsions, and b) the possible involvement of changes in alveolar surfactant in this through direct stimulation of the sympathetics to the lung by electrical stimulation of the stellate ganglion in monkeys and cats. 5. To investigate the transmural transmission of O2 through larger precapillary arteries. Preliminary experiments showing positive results have already been carried out on rabbit arteries.